Clinical Pharmacokinetics Flashcards Preview

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Flashcards in Clinical Pharmacokinetics Deck (17):
1

What is F for IV administration?

100%

2

How does ionization affect distribution?

nonionized forms are more readily distributed

3

Why are tube feeds important factors for oral/enteral administration?

- where does the tube feed end
- will the drug be absorbed in that location
- will the drug be able to travel through a tube feed

4

Why shouldn't you crush sustained release drugs?

makes it more bioavailable

5

Describe the impact of thick vs. thin skin on topical absorption.

thicker skin is less absorptive because it has more layers
thinner skin may be too absorptive and can increase concentration levels

6

How does perfusion rate affect distribution?

lower perfusion rate limits exposure to drug
- decreased absorption/distribution
- must increase dose

7

How does protein binding affect Vd?

- high binding = low Vd
- low binding (more free) = high Vd

8

How does BBB affect pharmacokinetics?

- if meninges are inflamed, spaces are increased and there is better distribution of the drug
- if meninges are noninflamed, spaces are tighter and there is minimal penetration of the BBB
- low protein binding drugs cross the BBB more easily

9

Define Phase I and Phase II hepatic metabolism.

Phase I - redox, hydrolysis via cytochrome P450 enzymes
Phase II - conjugation (acetylation, sulfation, glucuronidation)

10

How does CrCL change with age?

renal function decreases with age

11

How does hemodialysis affect pharmacokinetics?

may filter out small, hydrophilic drugs

12

How do neonates vary from population pharmacokinetics?

- thinner skin, more absorption of topical administration
- increased ECF (puffy) => increased absorption of hydrophilic drugs
- immature kidneys => decreased elimination

13

How do elderly patients vary from population pharmacokinetics?

- thinner skin, more absorption of topical administration
- increased adipose => increased absorption of fat-soluble drugs
- decreased ECF => decreased Vd
- renal function decreases with age

14

What is steady state dependent on?

half-life

15

Why is steady state important?

- prevents over and under-dosage
- assumes maximum and stable dosage

16

List types of drug interactions.

drug-drug
drug-nutrient
drug-disease
level of drug

17

List causes of drug interactions.

drug incompatibility
- precipitation with Ca or NaCl
absorption
- chelation
- stomach pH
distribution
- competition for binding sites
- changes in protein binding for disease states
- changes in ECF or adipose
metabolism
- inducer of CYP450 increases hepatic metabolism
- inhibitor of CYP450 decreases hepatic metabolism
elimination
- renal is most common
- competition
pharmacodynamics
- food interactions
- disease states
- some meds prolong QT intervals
- immunosuppressants
- some meds increase BG (steroids)